In a gas turbine, air pressurized by a compressor is mixed with fuel by a combustor so as to generate combustion gas which is a high-temperature fluid, and the combustion gas is introduced into a combustion gas flow channel of a turbine in which vanes and blades are alternately arranged. In addition, the blades and a rotor are rotated by the combustion gas circulating inside the combustion gas flow channel. In this manner, energy of the combustion gas is output as rotational energy, and the compressor or a generator is provided with a rotational drive force.
In the combustor of the gas turbine, in order to supply the high-temperature, high-pressure combustion gas to the turbine, components such as a transition piece and a combustor basket are exposed to the high-temperature combustion gas. For this reason, the components used in the combustor have a structure which introduces cooling air or steam in order to cool the components which become hot.
For example, Patent Document 1 discloses a structure which allows the steam to pass through a refrigerant passage by disposing a cooling jacket in which the refrigerant passage is formed on an outer periphery side of the transition piece of the combustor. The cooling jacket has multiple ribs which suppress the deformation caused by the pressure inside the refrigerant passage being increased by high-pressure steam. In order to form the refrigerant passage thereinside, these ribs are formed integrally with a plate material which forms a wall surface of the cooling jacket. Therefore, when the ribs are connected to an outer peripheral surface of the transition piece, welding cannot be performed from the inside of the cooling jacket which is on the refrigerant passage side. Consequently, the ribs are connected to the outer peripheral surface of the transition piece by welding only the outsides thereof.